The present invention relates generally to surface maintenance or conditioning machines, and more particularly to those machines employing one or more surface maintenance or conditioning appliances or tools to perform a hard floor surface wet scrubbing task.
Hard floor surface scrubbing machines are widely used to clean the floors of industrial and commercial buildings. They range in size from a small model which may clean a path ranging from 15 inches up to 36 inches wide controlled by an operator walking behind it, to a large model cleaning a path as wide as five feet controlled by an operator riding on the machine. Such machines in general are wheeled vehicles with suitable operator controls. Their bodies contain power and drive means, a solution tank to hold a cleaning liquid and a recovery tank to hold soiled solution recovered from the floor being scrubbed. The cleaning liquid may be water and a chemical detergent. The detergent typically includes a solvent, builder, and surfactant. Builders and surfactants provide for foam generation and foam stability. A scrub head which contains one or more scrubbing brushes and associated drive means are attached to the vehicle and may be located in front of, under or behind it. A solution distribution system dispenses cleaning liquid from the solution tank to the floor in the vicinity of the scrubbing brush or brushes. For a typical scrubber with a 32 inch wide scrub swath, the solution distribution rate varies between 0.5 gallons per minute (GPM) to 1.0 GPM.
Hard floor surface scrubbing machines typically further include a system to recover soiled scrubbing solution from the floor after it has been scrubbed. A solution recovery system may be a vacuum system including, for example, a double lipped vacuumized squeegee that wipes the floor behind the scrub head and collects the soiled scrubbing solution of water, detergent and soilage that has been loosened from the floor. The soiled scrubbing solution may include foam or froth generated by mechanical action of the brushes against the cleaning solution and the hard floor surface. Additional amounts of foam may be generated through the vacuum recovery process. Foam (air expanded cleaning solution) has heretofore been a shortcoming of prior art scrubbers as foam occupies a significantly greater volume as compared to the volume of unexpanded cleaning solution. Excessive foam within the recovery tank can necessitate shutting down the machine and emptying the recovery tank before the solution tank is empty, which reduces the productivity of the machine. As a result, foam elimination or reduction techniques have included specifically adapted enlarged solution recovery tanks and the addition of defoaming chemicals to the recovered solution tank.
Other limitations of vacuum systems for soiled solution recovery include power requirements, noise generation, and reliability. An alternative to vacuum-based soiled solution recovery systems for use upon a hard floor surface scrubbing machine would be desired.
One limitation of prior art scrubbers has been a relatively limited operational run time. For a typical scrubber with a 32 inch wide scrub swath and 30 gallon solution tank, the solution distribution rate varies between 0.5 GPM to 1.0 GPM. Run time based on solution capacity is between approximately 30 to 40 minutes. Merely increasing the size of the cleaning solution tanks is not a viable solution to achieving increased machine run times. An increase in cleaning solution capacity typically necessitates modifications to the frame and motive components, all of which result in additional weight and energy requirements for such a device. To the contrary, a need exists for a device having an increased run time achieved by reducing the amount of water required for the scrubbing process.
Another aspect of prior art scrubbers is the inefficient use of cleaning liquid in the scrub process. A relatively large amount of cleaning liquid is utilized to ensure wetting of the floor surface. The scrub process generates a relatively large amount of soiled cleaning liquid, most of which is recovered by the scrubber. Disposal of soiled solution in some applications remains an issue, especially where the cleaning process removes harmful or hazardous chemicals. Special handling or additional costs may be incurred to properly dispose a particularly soiled solution. By reducing the amount of water needed to perform a scrubbing process, a concomitant reduction in the amount of soiled solution is achieved. A need exists for a cleaning process providing efficient usage of cleaning solution.
The prior art discloses devices for cleaning surfaces, namely carpets, utilizing foam generation systems and mechanical brushes. These devices have utilized a variety of foam generation systems and recovery systems. Examples of such foam cleaning devices include U.S. Pat. Nos. 3,761,987; 3,931,662; and 5,813,086.
Nayfa et al (U.S. Pat. Nos. 3,761,987 and 3,931,662) discloses a machine for scrubbing or shampooing rugs or carpeted floor surfaces, for scrubbing hard floor surfaces, or for waxing and polishing hard floor surfaces. Stated objects of the invention of Nayfa et al. include:
an improved floor surface cleaning machine having the capability to shampoo and remove surface dirt from a carpet surface in one operation, to scrub and remove surface dirt from a hard floor surface in one operation, or to apply wax to and polish a floor surface in one operation,
a floor surface cleaning machine having a cleaning solution foaming system within the machine and a pressurized foam dispensing system,
a rug cleaning machine having means for scrubbing the pile, removing the dirt from the pile, and lifting the pile to original position in one operation,
a rug cleaning machine wherein the machine support and drive rollers function as squeegies to direct the cleaning foam and entrapped dirt toward the vacuum pickup nozzles, and
a floor surface cleaning machine having an improved solution dispensing mechanism including means for forming a foam, means for effecting flow of the foam under pressure, and means for controlling the rate of flow of foam to the floor surface.
These devices have not addressed limitations of prior art floor scrubbers, such as efficient cleaning solution usage in a hard floor surface scrubbing process.
Briefly stated, an improved hard floor surface scrubbing machine according to the present invention includes an aerator for generating a foam-like aerated cleaning liquid, one or more scrub brushes for engaging aerated cleaning liquid and the hard floor surface, and a soiled solution recovery system for removing soiled solution from the hard floor surface. A variety of liquid aerators may be utilized to practice the present invention. A particularly preferred aerator includes a pressurized air source, a pressurized cleaning liquid source, and a plurality of mixing elements for generating the aerated cleaning liquid. Alternative soiled solution recovery systems may be utilized in embodiments of the present invention.
An object of the present invention is to overcome the drawbacks of the conventional technology and to provide an efficient hard floor surface scrubbing machine.
Another object of the present invention is to provide a hard floor surface scrubbing machine which utilizes a foamed cleaning liquid in an efficient scrubbing process. The cleaning liquid may be water and a chemical surfactant. The aerated cleaning liquid may be generated via a variety of known aeration devices or systems. The aerated cleaning liquid permits a substantial reduction in the amount of cleaning solution liquid required in a scrub cleaning process. The reduction of cleaning liquid requirements may translate into decreased machine size and/or increased machine run times. Additionally, the amount of soiled cleaning solution which may require special disposal or additional handling may be reduced.
An aspect of the present invention is the provision of a cleaning liquid which can be efficiently aerated via known aeration devices, applied to a surface during a scrubbing process, and be rapidly dearated prior to a soiled solution recovery process.
Another aspect of the present invention is the provision of a cleaning liquid which may be efficiently aerated to a foam-like consistency, applied to the floor surface, and quickly dearated by engagement with a scrub brush. In a preferred embodiment of the present invention, the foam-like aerated cleaning liquid is substantially dearated by the scrub brush prior to soiled solution recovery.
Another aspect of the present invention is the provision of a defoaming device for de-aerated foamed soiled solution recovered during machine operation. The defoaming device may include a chemical-based defoamant, or may include a radiant heating element to thermally de-aerate the recovered foam.
Another aspect of the present invention is to provide a chemical dosing or metering system for combining a chemical with water to create a cleaning liquid during operation of the machine. In one embodiment of the invention, a machine may have a clean water tank and a chemical dosing system for combining water and a chemical prior to aeration. The chemical dosing system may include a configured removable chemical cartridge adapted to engage a correspondingly configured portion of the cleaning machine. The chemical dosing system may include active or passive elements for combining a chemical with water to create the cleaning liquid.
Yet another aspect of the present invention is a process for cleaning hard floor surfaces including the steps of aerating a cleaning liquid to form an aerated cleaning liquid, selectively conveying the aerated cleaning liquid to the hard floor surface and a rotating scrub brush, engaging the hard floor surface and the aerated cleaning liquid with the rotating scrub brush to loosen soil from the hard floor surface and to create a soiled solution of cleaning liquid and soil, and removing at least a portion of the soiled solution from the hard floor surface through the fluid recovery system.